地源热泵系统冷热负荷不平衡对土壤温度的影响

发布时间：2018-03-20 12:10

本文选题：地源热泵　切入点：冷热负荷不平衡率　出处：《东华大学》2013年硕士论文　论文类型：学位论文

【摘要】：地埋管地源热泵系统依靠地埋管换热器从地下土壤中获取能量,虽然热泵机组的热源和热汇都是地埋管周围扩散半径范围内的土壤,但由于气候差异,地埋管换热器夏季累计向土壤的放热量与冬季累计从土壤的取热量往往不一致,长期取热量与放热量不平衡会造成土壤温度不断偏离初始温度,并导致地源热泵系统运行效率逐年下降,这个问题已经引起各界对地源热泵技术长期运行效果的担心和关注。本文首先分析了建筑物冷热负荷的特性,不同功能的建筑由于使用时间、人员密度、散热设备开启时间等因素不同,其负荷总量、负荷强度和负荷的持续时间都是不同的,在地源热泵系统中,建筑的负荷特性决定了地埋管换热器的工作时间、热量累积、换热强度,直接影响地埋管换热器的换热性能。其次,通过分析几种常用的地埋管换热器传热模型,系统地阐述土壤温度场的模拟方法,并采用DST模型建立了地埋管换热器传热数学模型,模拟计算地埋管换热器与土壤之间的传热问题,研究地埋管区域土壤温度的变化情况。然后,以学院实验室部分房间为对象,设计地源热泵系统、地埋管换热器和数据采集处理系统等,搭建了实验平台,实验研究负荷变化对土壤温度的影响,并验证了地埋管换热器传热模型模拟计算的准确性。最后,以间歇负荷特性的办公建筑和连续负荷特性的宾馆建筑为例,模拟计算这两类建筑的地源热泵系统在相同气候条件下的长期运行性能,研究地埋管换热器周围土壤温度的变化,通过分析得到：从全年土壤热平衡角度考虑,在主要考虑建筑负荷总量影响时,松江地区办公建筑地源热泵系统所能承受的冷热负荷不平衡率为26%,宾馆建筑所能承受的冷热负荷不平衡率为16%。可见,如果建筑冷热负荷不平衡超过土壤自身对热量的扩散能力,就会引起土壤热失衡,不同功能的建筑由于负荷特性不同,土壤所能承受的冷热负荷不平衡率是不同的,因此,在设计时有必要对建筑的负荷特性进行分析,以论证在项目当地的水文地质和气象条件下系统所能承受的冷热负荷不平衡率,否则要采取相应的优化措施。
[Abstract]:Ground source heat pump system relies on underground heat exchanger to obtain energy from underground soil. Although the heat source and heat sink of heat pump unit are both the soil in the range of diffusion radius around the buried pipe, but because of the climate difference, The accumulated heat release from the soil in summer is often inconsistent with that from the soil in winter, and the long-term imbalance between heat removal and heat release will cause the soil temperature to deviate from the initial temperature continuously. The operation efficiency of ground-source heat pump system has been decreased year by year, which has caused concern and concern about the long-term operation effect of ground-source heat pump technology. In this paper, the characteristics of cooling and heat load of buildings are analyzed firstly. Because of the different factors such as service time, personnel density, opening time of heat dissipation equipment, the total load, the load intensity and the load duration are different in different function buildings. In the ground source heat pump system, the load characteristics of the building determine the working time, heat accumulation and heat transfer intensity of the ground buried tube heat exchanger, which directly affect the heat transfer performance of the ground buried tube heat exchanger. Secondly, by analyzing several commonly used heat transfer models of underground tube heat exchanger, the simulation method of soil temperature field is described systematically, and the mathematical model of heat transfer of ground buried tube heat exchanger is established by using DST model. The heat transfer between the ground heat exchanger and the soil is simulated and the variation of soil temperature in the buried pipe area is studied. Then, taking some rooms in the laboratory of the college as the object, the ground source heat pump system, the ground heat exchanger and the data acquisition and processing system are designed, and the experimental platform is built to study the influence of the load change on the soil temperature. The accuracy of heat transfer model simulation is verified. Finally, taking office buildings with intermittent load characteristics and guesthouse buildings with continuous load characteristics as examples, the long-term operating performance of the ground-source heat pump system of these two buildings under the same climatic conditions is simulated and calculated. The variation of soil temperature around ground buried tube heat exchangers is studied. From the point of view of soil heat balance throughout the year, the influence of total building load on soil temperature is mainly considered. The unbalance rate of heat and cold load of office buildings in Songjiang area is 26 and that of hotel buildings is 16. It can be seen that if the unbalance of cold and heat load in buildings exceeds the capacity of heat diffusion of soil itself, it will cause the imbalance of soil heat and heat. Because of the different load characteristics of different buildings, the unbalance rate of cold and heat load that soil can bear is different. Therefore, it is necessary to analyze the load characteristics of the building in order to demonstrate the unbalance rate of cooling and heat load that the system can withstand under the local hydrogeological and meteorological conditions of the project, otherwise, corresponding optimization measures should be taken.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU831

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